Only keep the basic/necessary devices running. For instance your geyser does not need to be on backup as it consumes a lot of power and you will only lose 2°C in water temperature during the 2-2.5 hours load shedding by keeping off the backup system.
By installing LEDs or CFL lights (remember incandescent and dichroic downlights won’t do) all your lights can be added on backup power.
An induction or gas hob should be used for cooking while heating food should be done using a microwave oven.
Fridges and freezers can be powered by backup power, but normally it is not necessary if the unit’s doors stay closed.
AV systems and PCs are not very power hungry and can easily be powered by a backup system leaving you with those luxuries during load shedding.
Air-conditioning units and underfloor heating can be powered by a backup system, but will drastically increase costs.
To achieve the best back up results for your needs, you will need a properly sized deepcycle battery bank. Batteries are available in two types namely, lead acid (AGM, wet cells, GEL, silver-calcium etc.) and lithium batteries.
The AGM and Gel batteries are normally used in domestic installations, because it is maintenance free and could last up to 10 years.
Lithium batteries are the newest technology, but costs have inhibited its usage thus far.
A system can cost a fair amount, so if it is wrongly sized and/or if you buy cheap short-lived inverters, chargers and batteries, you may pay later when the system does not work, as it should.